module storage.attached {

  export class LocalStorageStorage implements AttachedStorage {

    constructor(private _localStorage: typeof localStorage) {

    }

    getKeys(lead: string, obj: any, callback: (error: Error) => void) {

      for (var i = 0; i < this._localStorage.length; i++) {

        var key = this._localStorage.key(i);

        if (key.length < lead.length) continue;

        if (key.slice(0, lead.length) !== lead) continue;

        obj[key] = null;

      }

      callback(null);

    }

    populate(obj: any, callback: (error: Error) => void) {

      for (var k in obj) if (obj.hasOwnProperty(k)) {

        obj[k] = this._localStorage.getItem(k);

      }

      callback(null);

    }

    update(obj: any, callback: (error: Error) => void) {

      for (var k in obj) if (obj.hasOwnProperty(k)) {

        var value = obj[k];

        if (value === null)

          this._localStorage.removeItem(k);

        else

          this._localStorage.setItem(k, value);

      }

      callback(null);

    }

  }

  export module LocalStorageStorage {

    export function detect(callback: (error: Error, storage: AttachedStorage) => void, windowOverride = window) {

      var localStorage = windowOverride.localStorage;

      if (!localStorage) {

        callback(new Error('Browser does not expose localStorage.'), null);

        return;

      }

      var absentFunctions: string[] = [];

      if (!localStorage.getItem) absentFunctions.push('getItem');

      if (!localStorage.setItem) absentFunctions.push('setItem');

      if (!localStorage.removeItem) absentFunctions.push('removeItem');

      if (absentFunctions.length) {

        return;

      }

      var storage = new LocalStorageStorage(localStorage);

      callback(null, storage);

    }

  }

}